Direct transformations between functional groups simplify the chemical landscape and allow more efficient execution of multistep synthetic routes. While phenols and benzoic acid derivatives are among the most common organic functionalities, the ways for transforming a phenol into an aryl carboxylic acid derivative, such as esters and amides of benzoic acid, are still limited.
Palladium-catalyzed carbonylation of aromatic triflates is a commonly used transformation known in the literature. See, for example, Barnard, C. F. J. Organometallics 2008, 27, 5402; Brennfuhrer, A.; Neumann, H.; Beller, M. Angew. Chem., Int. Ed. 2009, 48, 4114; Lou, R.; VanAlstine, M.; Sun, X.; Wentland, M. P. Tetrahedron Lett. 2003, 44, 2477; Rahman, O.; Kihlberg, T.; Långström, B. J. Org. Chem. 2003, 68, 3558; Rahman, O.; Kihlberg, T.; Långström, B. J. Chem. Soc. Perkin Trans. 1 2002, 2699; Gerlach, U.; Wollmann, T. Tetrahedron Lett. 1992, 33, 5499; Cacchi, S.; Lupi, A. Tetrahedron Lett. 1992, 33, 3939; Dolle, R. E.; Schmidt, S. J.; Kruse, L. I. J. Chem. Soc. Chem. Commun. 1987, 904; and Cacchi, S.; Ciattini, P. G.; Morera, E.; Ortar, G. Tetrahedron Lett. 1986, 27, 3931. The method suffers from the disadvantage that palladium is classified as a Class I metal (significant safety concern) in pharmaceuticals with permitted daily exposure of less 10 μg/day. See Committee for Human Medicinal Products (CHMP): Guideline on the Specification Limits for Residues of Metal Catalysts or Metal Reagents (Doc. Ref. CPMP/SWP/QWP/4446/2000).